Answer: The uses are as follows :D
1. Lithium: heat resistive ceramics, aircraft building, tritium production
2. sodium: coolant in nuclear reactors, soap making, street light manufacture (e.g. sodium vapor lamps)
3. Potassium: tanning of leather, manufacture of inks, making gunpowder
4. Rubidium: thermoelectric generator, making atomic clocks, working fluid in vapor turbines
5. Cesium: catalyst for hydrogenation of some organic compounds, vacuum tubes, photovoltaic cells
6. Francium: extremely radioactive and extremely rare so not used often
The answer is between Either A or D
